The veteran of 18 NHL seasons was injured Thursday during a 3-1 loss in Florida. X-rays confirmed the break, the Sabres said Saturday.
The 38-year-old native of Finland hopes he'll only miss two games but was unsure when he'd return.
"If you break a bone, it's four-to-six weeks," Numminen said. "I don't know what it is but with a toe you can see how it feels in the skate.
"I haven't talked to the doctors yet, but I'm sure it's not going to be that long."
Numminen had 15 assists while playing in Buffalo's first 28 games this season.
Andrej Sekera was called up from Rochester of the AHL on Saturday and made his NHL debut against Montreal.